View Compilation Error

0_0_38037597_16334.cpp: In function 'int main()':
0_0_38037597_16334.cpp:41:28: error: lvalue required as left operand of assignment
       fa[find(s[len-1]-'a')=find(s[0]-'a');
                            ^
0_0_38037597_16334.cpp:41:43: error: expected ']' before ';' token
       fa[find(s[len-1]-'a')=find(s[0]-'a');
                                           ^